How Long Do Solar Panels Last? Warranties vs Real Lifespan

"How long will it last" usually gets answered with "25 years," which is both roughly true and not very useful. A solar installation isn't one thing. Its parts age at completely different rates, and only one of them is likely to need replacing while you still own the house.

The panels

Panels degrade rather than fail. They lose a small fraction of output each year, typically a few tenths of a percent, with a slightly larger drop in year one as the cells settle. After 25 years a decent panel is usually still producing somewhere north of 80% of what it did new.

That's the reason panels come with two separate warranties, which get confused constantly:

• Product warranty covers manufacturing defects. Shorter.
• Performance warranty guarantees output stays above a stated percentage at a stated year. Much longer.

A panel that quietly underperforms isn't a defect claim. It's a performance claim, and proving one needs documentation most owners don't keep. Which is an argument for holding onto your commissioning paperwork and your monitoring history.

The inverter: the part that will need replacing

This is the honest answer to the question nobody asks. Inverters carry much shorter warranties than panels, and they're working hard every daylight hour in a hot country. Plan on replacing one at some point during the system's life and you won't be caught out.

It isn't a disaster when it happens. Inverter prices have fallen, swapping one is a day's work, and a newer unit often monitors better than what it replaced. It's a budgeted maintenance item, not a catastrophe. Ignore it and it'll feel like one.

Batteries, if you have one

Batteries age by cycles, not just years, which is why the chemistry matters so much. LiFePO4 runs to several thousand cycles at high depth of discharge; lead-acid gives you far fewer at half the usable depth. For a system cycling daily, that's the difference between one replacement and several. We went through the arithmetic in the battery comparison.

Mounting and wiring

Rarely discussed, quietly important. Coastal installations in particular live in salt air, and cheap fixings corrode. Stainless or properly coated hardware costs more and outlasts everything around it. Cable insulation degrades under UV if it hasn't been routed and clipped properly.

None of this is glamorous. All of it decides whether the system reaches twenty years intact.

What actually shortens a system's life

In rough order of how often we see it:

• Poor mounting, especially fixings that miss structure or corrode through
• Heat with no ventilation, above all around inverters and batteries
• Shade nobody accounted for, which stresses cells and encourages hot spots
• Never cleaning a coastal or dusty array
• Batteries run deeper and harder than their specification allows

Notice that four of those five are installation and ownership decisions. The equipment is usually not the limiting factor.

What to keep

Put these somewhere you'll find them in fifteen years: as-built diagram, panel and inverter warranty documents with serial numbers, commissioning readings, and your monitoring login. Warranty claims fail on missing paperwork far more often than they fail on merit.

Buying something that lasts

Most of what decides whether a system reaches twenty years is settled on the day it's installed, in choices you'll never see once the panels are up.

If you're thinking about solar, ask us what we use for mounting and fixings, and what the warranties actually cover. We'd rather answer that now than have you find out later. Message us on Messenger, call, or come by the shop in Concordia, Bolinao.